Emitting materials used for organic EL based on tridentate ligands

ABSTRACT

A series of emitting materials used for organic EL based on tridentate ligands are characterized as Formula 1, Formula 2 and Formula 3. where: I is a bidentate ligand such as 8-hydroxyquinoline and 2-(o-hydroxyphenyl)-benzoxazole, II, III are unsubstituted or substituted aryl groups. The substituted groups can have 1-8 carbon atoms, halogen, cyano, amino, amido, sulfonyl, carbonyl, aryl, or heteroalkyl groups. The ligand including II and III is a tridentate ligand with three chelate atoms: two oxygen atoms and one nitrogen atom. The central metal atoms can be trivalent or tetravalent atoms such as Al, In, Ga, Tl, and Sn. These materials can be used as emitting materials or electronic transport materials in organic EL devices.

BACKGROUND OF THE INVENTION

[0001] This invention relates to novel emitting materials for organic electroluminescence (EL) devices. As a promising technology for flat panel display, organic EL has attracted more and more attentions. The early efficient devices have been reported in C. W. Tang, S. A. Van Slyke, Appl. Phys. Lett. 1987, 51-913˜915 and U.S. Pat. No. 4,720,432 issued Jan. 19, 1988. Great improvements have been made since 1987 and many new materials have been synthesized and used in organic EL devices. There are diverse emitting materials used in fabrication of organic EL devices with blue, green, yellow, and red emission.

SUMMARY OF THE INVENTION

[0002] The primary object of this invention is provide to a series of stable complexes based on many kinds of tridentate ligands. These materials exhibited strong fluorescence and excellent amorphous properties in solid state. Both of these characters are conducive to forming high quality amorphous films.

[0003] Another object of the invention is provide to the use of such novel complexes as thermal stable emitting materials for organic light-emitting diodes (OLEDs).

[0004] This invention disclosed here a series of stable complexes which have a tridentate ligand. Almost all of these complexes have the high Tg more than 200° C. The advantage of these materials lies in their excellent thermal stability and good performance to form amorphous films. The materials in this invention have made some progress in improving the compatibility with other layers materials. These materials have some unique characteristics that will be conducive to forming high quality amorphous films. Such novel complexes can be used as a thermal stable emitting material for OLEDs. In addition, a series of emitting colors have been obtained from these materials including green, yellow, and red, some of which are remain rare now. And the color position in the color coordinates system shows strong potential as a red light-emitting material for organic electroluminescence. These materials can be used as emitting materials or electronic transport materials in organic EL devices.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005]FIG. 1 is the NMR-H′ spectrum of Complex 1.

[0006]FIG. 2 is the mass spectrum of Complex 1.

[0007]FIG. 3 is the high-resolution mass spectrum of Complex 1.

[0008]FIG. 4 is the computer search result of the high-resolution mass spectrum of Complex 1.

[0009]FIG. 5 is the high-resolution mass spectrum of Complex 12.

[0010]FIG. 6 is the computer search result of the high-resolution mass spectrum of Complex 12.

[0011]FIG. 7 is the color position in the color coordinates system (CIE 1931) for the device 3 comprising Complex 12, with the following layer structure: ITO/TPD/Complex 12 (100:1˜15:1 by weight) (60 nm)/Alq3 (40 nm)/MgAg (10:1).

[0012]FIG. 8 is the EL spectra for the device 1 comprising Complex 23, with the following layer structure: ITO/TPD (60 nm)/Complex 23/MgAg (10:1)

DETAILED DESCRIPTION OF THE INVENTION

[0013] In accordance with the present invention, a series of emitting materials used for organic EL based oil tridentate ligands are characterized as Formula 1, Formula 2 and Formula 3. where: I is a bidentate ligand such as 8-hydroxyquinoline and 2-(o-hydroxyphenyl)-benzoxazole, II, III are unsubstituted or substituted aryl groups. The substituted groups can have 1-8 carbon atoms, halogen, cyano, amino, amido, sulfonyl, carbonyl, aryl, or heteroalkyl groups. The ligand including II and III is a tridentate ligand with three chelate atoms: two oxygen atoms and one nitrogen atom. The central metal atoms can be trivalent or tetravalent atoms such as Al, In, Ga, Tl, and Sn.

[0014] These emitting materials should possess good thermal stability and high purity. The glass transition temperature (Tg) is a key parameter to determine the stability of the amorphous materials. The high Tg could minimize the probability of the crystallization in amorphous thin films, especially under the condition of a high temperature. The Tg of tris(8-hydroxyquinoline) aluminum (Alq3) is about 175° C., far below its decomposing temperature. Almost all of these complexes according to the invention have the high Tg more than 200° C. Meanwhile, these materials can be used as emitting materials or electronic transport materials in organic EL devices.

[0015] Typical complexes of the Formula 1 were shown in below table 1. TABLE 1 I 8-hydroxy- 5-Cl-8-hydroxy- 2-(o-hydroxyphenyl)- II, III quinoline quinoline benzoxazole II = phenyl Complex 1 Complex 2 Complex 3 III = phenyl II = 1,2 Complex 4 Complex 5 substituted naphthyl III = phenyl II = 2,3 Complex 6 substituted naphthyl III = phenyl II = 3,4 Complex 7 substituted naphthyl III = phenyl II = phenyl Complex 8 Complex 9 III = 1,2 substituted naphthyl II = phenyl Complex 10 III = 2,3 substituted naphthyl II = phenyl Complex 11 III = 3,4 substituted naphthyl

[0016] According to the definitions in table 1, it is obvious that the Complexes 1-11 have the following constitutional structures respectively.

[0017] Typical complexes of the Formula 2 were shown in below table 2. TABLE 2 I 2-(o-hydroxy- 8-hydroxy- 5-Cl-8-hydroxy- phenyl)- II, III quinoline quinoline benzoxazole L1 II = phenyl Complex 12 Complex 13 Complex 14 III = phenyl L2 II = 1,2 Complex 15 Complex 16 substituted naphthyl III = phenyl L3 II = 2,3 Complex 17 substituted naphthyl III = phenyl L4 II = 3,4 Complex 18 substituted naphthyl III = phenyl L5 II = phenyl Complex 19 Complex 20 III = 1,2 substituted naphthyl L6 II = phenyl Complex 21 III = 2,3 substituted naphthyl L7 II = phenyl Complex 22 III = 3,4 substituted naphthyl

[0018] According to the definitions in table 2, it is obvious that the Complexes 12-22 have the following constitutional structures respectively.

[0019] Typical complexes of the Formula 3 were shown in below table 3. TABLE 3 II 1,2 2,3 3,4 substituted substituted substituted III phenyl naphthyl naphthyl naphthyl phenyl Complex 23 Complex 27 Complex 28 Complex 29 1,2 substituted Complex 24 naphthyl 2,3 substituted Complex 25 naphthyl 3,4 substituted Complex 26 naphthyl

[0020] According to the definitions in table 3, it is obvious that the Complexes 23-29 have the following constitutional structures respectively.

[0021] All the above these compounds can be prepared by the following two steps: the first step is the synthesis of the tridentate ligands, the second step is the synthesis of the objective complexes.

[0022] The first step is the synthesis of the tridentate ligands. The ligands described in Formula 1 and Formula 3 are shiff bases, which can be synthesized by conventional shiff base synthesis methods comprising the steps: heating the mixture of o-hydroxy-aryl aldehyde and o-hydroxy-aryl alcohol and recrystallization in an organic solvent. The ligands described in Formula 2 can be synthesized by the method of Willstatter (Anal. Chem., 35,1144).

[0023] The second step includes a chemical reaction in an organic solvent controlled by organic bases. Inorganic aluminum salts or organic aluminum compounds in solvent are added with the solution of ligands. The product was collected by filtration and washed with solvents. The compounds were further purified by the train sublimation method.

[0024] The EL devices are fabricated by conventional vacuum vapor deposition method under a vacuum condition or spin coating method at room temperature. As described above, said complexes can be used in OLEDs serving as emitting materials or electron transport materials. When used as electron transport and emitting layers in the EL devices, they are heated by conventional vacuum vapor deposition method; when used as dyes of these layers in the EL devices, they also can be treated with spin coating method.

[0025] The OLEDs are fabricated on the ITO coated glasses after carefully cleaning. The material is vaporized to form a thin layer after a thin layer of hole transport material was prepared on a glass plate. The electron transport layer is optional for OLEDs. As the last step, a thin film of metal that is used as cathode is formed by conventional vacuum vapor deposition method.

[0026] The advantage of these materials lies in their excellent thermal stability and good performance to form amorphous films. Some incompatibilities with the hole transport materials also exist in many emitting complexes that would lead to phase separation. The materials in this invention have made some progress in improving the compatibilities with other layers materials. These materials have some unique characteristics that will be conducive to forming high quality amorphous films. Such novel complexes can be used as a thermal stable emitting material for OLEDs. In addition, a series of emitting colors have been obtained from these materials including green, yellow, and red, some of which are remain rare now. And the color position in the color coordinates system shows strong potential as a red light-emitting material for organic electroluminescence. The introductions of tridentate ligands in the complex structure open a new route for exploring new materials for organic EL.

[0027] The following non-limiting example further serves to illustrate the invention.

[0028] As described below, the example 1˜example 11 are directed to the preparation and use of Complex 1˜Complex 11.

EXAMPLE 1 Complex 1

[0029] Synthesis of the Complex 1:

[0030] Complex 1 was synthesized through a reaction in the ethanol solution of 8-hydroxyquinoline, salicylidene-o-aminophenol and AlCl₃ as follows. First, a solution of 8-hydroxyquinioline (0.05M) and piperidine (0.05M) in 100 ml ethanol was added to a solution of AlCl₃.6H₂O (0.5M) in 10 ml ethanol very slowly with an intensive stirring. Then, a solution of salicylidene-o-aminophenol (0.01M) and piperidine (0.02M) in 500 ml ethanol was introduced slowly. The mixture was stirred for about 1 hour and cooled to room temperature and kept in dark for about 10 hours. A yellow precipitate was formed when equivalent amount water was poured into the solution. The product was collected by filtration and washed with ethanol rapidly, then dried under an infrared lamp. The obtained product power showed strong yellow fluorescence under an ultraviolet lamp. The materials were further purified by an improved train sublimation method. The salicylidene-o-aminophenol ligand was obtained by heating the mixture of 2-aminophenol and 2-hydroxy-salicylic aldehyde in ethanol solution and the following recrystallization. The molecular structure of Complex 1 was supported by high-resolution mass spectrum (MS) shown in FIG. 3, nuclear magnetic resonance (NMR) shown in FIG. 1 and element analysis. High-resolution MS found: 382.08793. Calc. for C22H15O3N2Al: 382.08981 (shown in FIG. 4); Element analysis found: C, 68.85; H, 3.83; N, 7.17. Calc. For Complex 1: C, 69.11; H, 3.93; N, 7.33.

[0031] Fabrication of four EL devices with complex 1:

[0032] 1. (device 1) The EL device was fabricated by conventional vacuum vapor deposition method under a 2×10⁻³ Pa vacuum at room temperature. For example, the methods can be found in the following references: C. W. Tang and S. A. Vanslyke: Appl. Phys. Lett. 51 (1987) 913; Zilan Shen, Paul E. Burrows, Vladimir Bulovic, Stephen R. Forrest and Mark E. Thompson: Science 276(1997) 2009; Philip S. Bryan, Frank V. Lovecchio, Steven A. Vanslyke, Rochester: U.S. Pat. No. 5,141,671 (1992). N,N′-diphenyl-N,N′-di(m-methylphenyl)benzidine (TPD) was used as the hole transport layer material. The following layer structures of were prepared: indium-tin-oxide (ITO)/TPD (60 nm)/Complex 1 (40 nm)/MgAg(10:1). The maximum brightness of the device was up to 2000 cd/m². The EL emission was at around 573 nm and the maximum luminous efficiencies up to 1.5 lm/W, which was shown in table 5.

[0033] 2. (device 2) The EL device was fabricated by conventional vacuum vapor deposition method under a 2×10-3 Pa vacuum at room temperature. N,N′-diphenyl-N,N′-di(m-methylphenyl)benzidine (TPD) was used as the hole transport layer material. The following layer structure of devices was prepared: ITO/TPD (60 nm)/Complex 1 (40 nm)/Alq3 (20 nm)/MgAg (10:1). The maximum brightness of the device was up to 3000 cd/m². The EL emission was at around 573 nm and the maximum luminous efficiencies up to 1.7 lm/W, which was shown in table 5.

[0034] 3. (device 3) The EL device was fabricated by conventional vacuum vapor deposition method under a 2×10-3 Pa vacuum at room temperature. N,N′-diphenyl-N,N′-di(m-methylphenyl)benzidine (TPD) was used as the hole transport layer material. The following layer structures of was prepared: ITO/TPD; Complex 1 (100:1˜15:1 by weight) (60 nm)/Alq3 (40 nm)/MgAg (10:1). The maximum brightness of the device was up to 2500 cd/m². The EL emission was at 535˜577 nm (depending on the concentration of Complex 1 in the thin film) and the maximum luminous efficiencies up to 1.8 lm/W, which was shown in table 5.

[0035] 4. (device 4) Both Complex 1 and some polymer (such as poly(N-vinylcarbazole) (PVK)) were dissolved in some organic solvent (such as C2H4Cl2). The thin film of mixture of Complex 1 and polymer was prepared by spin coating method. The following layer structures of was prepared: ITO/PVK: Complex 1 (100:1˜15:1 by weight) (60 nm)/Alq3 (40 nm)/MgAg (10:1). The maximum brightness of the device was up to 1800 cd/m². The EL emission was at 505˜573 nm (depending on the concentration of Complex 1 in the thin film) and the maximum luminous efficiencies up to 1.8 lm/W, which was shown in table 5.

EXAMPLE 2 Complex 2

[0036] According to the synthesis procedures of Complex 1, Complex 2 was prepared by replacing 8-hydroxyquinoline with 5-Cl-8-hydroxyquinoline. The data for identifying this complex was shown in the following table 4.

[0037] The four kinds of devices were prepared similar to the processes of Complex 1. The performances of these devices were shown in the following table 5.

EXAMPLE 3 Complex 3

[0038] According to the synthesis procedures of Complex 1, Complex 3 was prepared by replacing 8-hydroxyquinoline with 2-(o-hydroxyphenyl)-benzoxazole. The data for identifying this complex was shown in the following table 4.

[0039] The four kinds of devices were prepared similar to the processes of Complex 1. The performances of these devices were shown in the following table 5.

EXAMPLE 4 Complex 4

[0040] According to the synthesis procedures of Complex 1, Complex 4 was prepared by replacing 2-hydroxy-salicylic aldehyde with 2-hydroxy-naphthyl aldehyde. The data for identifying this complex was shown in the following table 4.

EXAMPLE 5 Complex 5

[0041] According to the synthesis procedures of Complex 4, Complex 5 was prepared by replacing 8-hydroxyquinoline with 5-Cl-8-hydroxyquinoline. The data for identifying this complex was shown in the following table 4.

EXAMPLE 6 Complex 6

[0042] According to tie synthesis procedures of Complex 4, Complex 6 was prepared by replacing 2-hydroxy-naphthyl aldehyde with 3-hydroxy-2-naphthyl aldehyde. The data for identifying this complex was shown in the following table 4.

EXAMPLE 7 Complex 7

[0043] According to the synthesis procedures of Complex 4, Complex 7 was prepared by replacing 2-hydroxy-naphthyl aldehyde with 1-hydroxy-2-naphthyl aldehyde. The data for identifying this complex was shown in the following table 4.

EXAMPLE 8 Complex 8

[0044] According to the synthesis procedures of Complex 4, Complex 8 was prepared by replacing 2-aminophenol with 2-hydroxy-1-naphthyl amine. The data for identifying this complex was shown in the following table 4.

EXAMPLE 9 Complex 9

[0045] According to the synthesis procedures of Complex 8, Complex 9 was prepared by replacing 8-hydroxyquinoline with 5-Cl-8-hydroxyquinoline. The data for identifying this complex was shown in the following table 4.

EXAMPLE 10 Complex 10

[0046] According to the synthesis procedures of Complex 4, Complex 10 was prepared by replacing 2-aminophenol with 3-hydroxy-2-naphthyl amine. The data for identifying this complex was shown in the following table 4.

EXAMPLE 11 Complex 11

[0047] According to the synthesis procedures of Complex 4, Complex 11 was prepared by replacing 2-aminophenol with 1-hydroxy-2-naphthyl amine. The data for identifying this complex was shown in the following table 4. TABLE 4 Production Cal. for Complex yield Structural Formula Element analysis No. % C % H % N % C % H % N % 1 75 69.11 3.93 7.33 68.8 3.8 7.17 2 68 63.39 3.36 6.72 62.9 3.27 6.82 3 70 69.64 3.80 6.25 70.2 3.79 6.20 4 74 72.22 3.94 6.48 73.1 3.82 6.56 5 64 66.88 3.43 6.00 67.7 3.29 6.18 6 72 72.22 3.94 6.48 72.7 3.84 6.53 7 63 72.22 3.94 6.48 73.1 3.86 6.51 8 74 72.22 3.94 6.48 73.4 3.83 6.54 9 69 66.88 3.43 6.00 67.1 3.40 6.11 10  66 72.22 3.94 6.48 72.9 3.89 6.53 11  61 72.22 3.94 6.48 73.2 3.88 6.50

[0048] TABLE 5 Device No. Complex 1 Complex 2 Complex 3 1 Brightness/cd/m² 2000    800    600 (12V) The maximum  573    568    563 wavelength/nm 2 Brightness/cd/m² 3000   1000    900 (12V) The maximum  573    567    562 wavelength/nm 3 Brightness/cd/m² 2500 >1500 >1100 (12V) The maximum 535˜577 537˜569 538˜566 wavelength/nm 4 Brightness/cd/m² 1800 >1200  >860 (12V) The maximum 505˜573 531˜569 537˜564 wavelength/nm

[0049] The following example 12˜example 22 are directed to the preparation and use of Complex 12˜Complex 22, in which L1˜L7 represent the tridentate ligands listed in table 2.

EXAMPLE 12 Complex 12

[0050] Synthesis of the Complex 12:

[0051] Complex 12 was synthesized through a reaction in the ethanol solution of 8-hydroxyquinoline, o,o′-dihydroxyazobenzene (L1) and AlCl₃. First, a solution of 8-hydroxyquinoline (0.05M) and piperidine (0.05M) in 100 ml ethanol was added to a solution of AlCl₃.6H₂O (0.5M) in 10 ml ethanol very slowly with an intensive stirring. Then, a solution of L1 (0.01M) and piperidine (0.02M) in 500 ml ethanol was introduced slowly. The mixture was stirred for about 1 hour and cooled to room temperature and kept in dark for about 10 hours. A scarlet precipitate was formed when equivalent amount water was poured into the solution. The product was collected by filtration and washed with ethanol rapidly, then dried under an infrared lamp. The obtained product power showed strong red fluorescence under an ultraviolet lamp. The materials were further purified by an improved train sublimation method. The L1 ligand was obtained by the typical synthesis method of azobenzene. The molecular structure of Complex 12 was supported by high-resolution mass spectrum (MS) shown in FIG. 5 and element analysis. High-resolution MS found: 383.0845240. Calc. for C21H14O3N3Al: 383.0845062 (shown in FIG. 6); Element analysis found: C, 65.9; H, 3.89; N, 10.68. Calc. For Complex 12: C, 65.80; H, 3.66; N, 10.97.

[0052] Fabrication of four EL devices with complex 12:

[0053] 1. (device 1) The EL device was fabricated by conventional vacuum vapor deposition method under a 2×10-3 Pa vacuum at room temperature. N,N′-diphenyl-N,N′-di(m-methylphenyl)benzidine (TPD) was used as the hole transport layer material. The following layer structures of was prepared: ITO/TPD (60 nm)/Complex 12(40 nm)/MgAg(10:1). The maximum brightness of the device was up to 120 cd/m² and the EL emission was at around 640 nm, which was shown in table 8.

[0054] 2. (device 2) The EL device was fabricated by conventional vacuum vapor deposition method under a 2×10-3 Pa vacuum at room temperature. N,N′-diphenyl-N,N′-di(m-methylphenyl)benzidine (TPD) was used as the hole transport layer material. The following layer structures of was prepared: ITO/TPD (60 nm)/Complex 12(40 nm)/Alq3 (20 nm)/MgAg(10:1). The maximum brightness of the device was up to 150 cd/m² and the EL emission was at around 635 nm, which was shown in table 8.

[0055] 3. (device 3) The EL device was fabricated by conventional vacuum vapor deposition method under a 2×10-3 Pa vacuum at room temperature. N,N′-diphenyl-N,N′-di(m-methylphenyl)benzidine (TPD) was used as the hole transport layer material. The following layer structures of was prepared: ITO/TPD; Complex 12 (100:1˜15:1 by weight) (60 nm)/Alq3 (40 nm)/MgAg (10:1). The maximum brightness of the device was up to 150 cd/m² and the EL emission was at 625˜645 nm (depending on the concentration of Complex 1 in the thin film), which was shown in table 8.

[0056] 4. (device 4) Both Complex 1 and some polymer (such as PVK) were dissolved in some organic solvent (such as C2H4Cl2). The thin film of mixture of Complex 1 and polymer was prepared by spin coating method. The following layer structures of was prepared: ITO/PVK: Complex 12 (100:1˜15:1 by weight) (60 nm)/Alq3 (40 nm)/MgAg (10:1). The maximum brightness of the device was up to 130 cd/m² and the EL emission was at 605˜645 nm (depending on the concentration of Complex 1 in the thin film), which was shown in table 8.

EXAMPLE 13 Complex 13

[0057] According to the synthesis procedures of Complex 12, Complex 13 was prepared by replacing 8-hydroxyquinoline with 5-Cl-8-hydroxyquinoline. The data for identifying this complex was shown in the following table 7.

EXAMPLE 14 Complex 14

[0058] According to the synthesis procedures of Complex 12, Complex 14 was prepared by replacing 8-hydroxyquinoline with 2-(o-hydroxyphenyl)-benzoxazole. The data for identifying this complex was shown in the following table 7.

EXAMPLE 15 Complex 15

[0059] According to the synthesis procedures of Complex 12, Complex 15 was prepared by replacing L1 with L2. The data for identifying this complex was shown in the following table 7.

EXAMPLE 16 Complex 16

[0060] According to the synthesis procedures of Complex 15, Complex 16 was prepared by replacing 8-hydroxyquinoline with 5-Cl-8-hydroxyquinoline. The data for identifying this complex was shown in the following table 7.

EXAMPLE 17 Complex 17

[0061] According to the synthesis procedures of Complex 15, Complex 17 was prepared by replacing L1 with L3. The data for identifying this complex was shown in the following table 7.

EXAMPLE 18 Complex 18

[0062] According to the synthesis procedures of Complex 15, Complex 18 was prepared by replacing L1 with L4. The data for identifying this complex was shown in the following table 7.

EXAMPLE 19 Complex 19

[0063] According to the synthesis procedures of Complex 15, Complex 19 was prepared by replacing L1 with L5. The data for identifying this complex was shown in the following table 7.

EXAMPLE 20 Complex 20

[0064] According to the synthesis procedures of Complex 19, Complex 20 was prepared by replacing 8-hydroxyquinoline with 5-Cl-8-hydroxyquinioline. The data for identifying this complex was shown in the following table 7.

EXAMPLE 21 Complex 21

[0065] According to the synthesis procedures of Complex 15, Complex 21 was prepared by replacing L1 with L6. The data for identifying this complex was shown in the following table 7.

EXAMPLE 22 Complex 22

[0066] According to the synthesis procedures of Complex 15, Complex 22 was prepared by replacing L1 with L7. The data for identifying this complex was shown in the following table 7. TABLE 7 Production Cal. for Complex yield Structural Formula Element analysis No. % C % H % N % C % H % N % 12 78 65.80 3.66 10.97  65.9 3.89 10.68  13 66 60.36 3.11 10.06  60.4 3.32 10.22  14 65 66.82 9.35 6.25 66.6 3.80 9.31 15 69 69.28 3.70 9.70 68.9 3.88 9.86 16 67 64.17 3.21 8.98 64.0 3.33 8.91 17 75 69.28 3.70 9.70 68.9 3.87 9.82 18 70 69.28 3.70 9.70 69.3 3.79 9.65 19 77 69.28 3.70 9.70 69.1 3.84 9.68 20 74 64.17 3.21 8.98 64.2 3.36 8.89 21 73 69.28 3.70 9.70 68.9 3.79 9.62 22 75 69.28 3.70 9.70 68.8 3.80 9.67

[0067] TABLE 8 Device No. Complex 12 1 Brightness/cd/m² (25V) 120 The maximum wavelength/nm 640 2 Brightness/cd/m² (25V) 150 The maximum wavelength/nm 635 3 Brightness/cd/m² (25V) 150 The maximum wavelength/nm 625˜645 4 Brightness/cd/m² (25V) 130 The maximum wavelength/nm 605˜645

[0068] The following example 23˜example 29 are directed to Complex 23˜Complex 29. All the tridentate ligands are the same as the tridentate ligands used in the first group complexes. So the synthesis of these ligands are referred to the example 1˜example 11.

EXAMPLE 23 Complex 23

[0069] Synthesis of the Complex 23:

[0070] Complex 23 was synthesized through a reaction in the ethanol solution of salicylidene-o-aminophenol and SnCl₄. The salicylidene-o-aminophenol ligand was obtained by heating the mixture of 2-aminophenol and 2-hydroxy-salicylic aldehyde in ethanol solution and the following recrystallization. A solution of salicylidene-o-aminophenol (0.01M) and piperidine (0.02M) in 500 ml ethanol was added to a solution of SnCl₄ (0.25M) in 10 ml ethanol very slowly with an intensive stirring. A light yellow precipitate was formed. The mixture was stirred for about 1 hour and cooled to room temperature and kept in dark for about 10 hours. The product was collected by filtration and washed with ethanol rapidly, then dried under an infrared lamp. The obtained product power showed strong yellow fluorescence under an ultraviolet lamp. The materials were further purified by an improved train sublimation method. The molecular structure of Complex 23 was supported by element analysis. Element analysis found: C, 57.68; H, 3.34; N, 5.18. Calc. For Complex 23: C, 57.703; H, 3.329; N, 5.178.

[0071] Fabrication of the devices with complex 23:

[0072] 1. (device 1) The EL device was fabricated by conventional vacuum vapor deposition method under a 2×10-3 Pa vacuum at room temperature. N,N′-diphenyl-N,N′-di(n-methylphenyl)benzidine (TPD) was used as the hole transport layer material. The following layer structures of was prepared: ITO/TPD (60 nm)/Complex 23(40 nm)/MgAg(10:1). The maximum brightness of the device was up to 2000 cd/m². The EL emission was at around 573 nm and the maximum luminous efficiencies up to 1.5 lm/W, which was shown in FIG. 8 and in table 10.

[0073] 2. (device 2) The EL device was fabricated by conventional vacuum vapor deposition method under a 2×10-3 Pa vacuum at room temperature. N,N′-diphenyl-N,N′-di(m-methylphenyl)benzidine (TPD) was used as the hole transport layer material. The following layer structures of was prepared: ITO/TPD (60 nm)/Complex 23 (40 nm)/Alq3 (20 nm)/MgAg (10:1). The maximum brightness of the device was up to 3000 cd/m2. The EL emission was at around 573 nm and the maximum luminous efficiencies up to 1.7 lm/W, which was shown in table 10.

[0074] 3. (device 3) The EL device was fabricated by conventional vacuum vapor deposition method under a 2×10-3 Pa vacuum at room temperature. N,N′-diphenyl-N,N′-di(m-methylphenyl)benzidine (TPD) was used as the hole transport layer material. The following layer structures of was prepared: ITO/TPD: Complex 23 (100:1˜15:1 by weight) (60 nm)/Alq3 (40 nm)/MgAg (10:1). The maximum brightness of the device was up to 2500 cd/m². The EL emission was at 535˜577 nm (depending on the concentration of Complex 1 in the thin film) and the maximum luminous efficiencies up to 1.8 lm/W, which was shown in table 10.

[0075] 4. (device 4) Both Complex 23 and some polymer (such as PVK) were dissolved in some organic solvent (such as C2H4Cl2). The thin film of mixture of Complex 1 and polymer was prepared by spin coating method. The following layer structures of was prepared: ITO/PVK: Complex 1 (100:1˜15:1 by weight) (60 nm)/Alq3 (40 nm)/MgAg (10:1). The maximum brightness of the device was up to 1800 cd/m². The EL emission was at 505˜573 nm (depending on the concentration of Complex 1 in the thin film) and the maximum luminous efficiencies up to 1.8 lm/W, which was shown in table 10.

EXAMPLE 24 Complex 24

[0076] According to the synthesis procedures of Complex 23, Complex 24 was prepared by replacing 2-hydroxy-salicylic aldehyde with 2-hydroxy-naphthyl aldehyde. The data for identifying this complex was shown in the following table 9.

EXAMPLE 25 Complex 25

[0077] According to the synthesis procedures of Complex 23, Complex 25 was prepared by replacing 2-hydroxy-naphthyl aldehyde with 3-hydroxy-2-naphthyl aldehyde. The data for identifying this complex was shown in the following table 9.

EXAMPLE 26 Complex 26

[0078] According to the synthesis procedures of Complex 23, Complex 26 was prepared by replacing 2-hydroxy-naphthyl aldehyde with 1-hydroxy-2-naphthyl aldehyde. The data for identifying this complex was shown in the following table 9.

EXAMPLE 27 Complex 27

[0079] According to the synthesis procedures of Complex 23, Complex 27 was prepared by replacing 2-aminophenol with 2-hydroxy-1-naphthyl amine. The data for identifying this complex was shown the following table 9.

EXAMPLE 28 Complex 28

[0080] According to the synthesis procedures of Complex 23, Complex 28 was prepared by replacing 2-aminophenol with 3-hydroxy-2-naphthyl amine. The data for identifying this complex was shown the following table 9.

EXAMPLE 29 Complex 29

[0081] According to the synthesis procedures of Complex 23, Complex 29 was prepared by replacing 2-aminophenol with 1-hydroxy-2-naphthyl amine. The data for identifying this complex was shown in the following table 9. TABLE 9 Production Cal. for Complex yield/ Structural Formula Element analysis No. % C % H % N % C % H % N % 23 89 57.70 3.33  5.18  57.68 3.34 5.18 24 82 60.94 3.386 4.740 60.76 3.42 4.80 25 79 60.94 3.186 4.740 60.81 3.43 4.79 26 80 60.34 3.386 4.740 60.77 3.46 4.81 27 63 60.94 3.386 4.740 60.72 3.38 4.78 28 71 60.94 3.386 4.740 60.69 3.49 4.88 29 61 60.94 3.386 4.740 60.73 3.50 4.82

[0082] TABLE 10 Device No. Complex 23 1 Brightness/cd/m² (15V)  85 The maximum wavelength/nm 606 2 Brightness/cd/m² (15V) 160 The maximum wavelength/nm 605 3 Brightness/cd/m² (15V) 210 The maximum wavelength/nm 575˜615 4 Brightness/cd/m² (15V) 160 The maximum wavelength/nm 565˜615 

What is claimed is:
 1. A compound of Formula 1 wherein I is a bidentate ligand such as 8-hydroxyquinoline and 2-(o-hydroxyphenyl)-benzoxazole, II and III are unsubstituted or substituted aryl groups.


2. A compound of Formula 2 wherein I is a bidentate ligand such as 8-hydroxyquinoline and 2-(o-hydroxyphenyl)-benzoxazole, II and III are unsubstituted or substituted aryl groups.


3. A compound of Formula 3 wherein II and III are unsubstituted or substituted aryl groups.


4. The compound of claim 1 wherein the subsituents of the aryl groups I, II or III are independently selected from the group consisting of 1-8 carbon atoms, halogen, cyano, amino, amido, sulfonyl, carbonyl, aryl, or heteroalkyl groups.
 5. The compound of claim 2 wherein the subsituents of the aryl groups I, II or III are independently selected from the group consisting of 1-8 carbon atoms, halogen, cyano, amino, amido, sulfonyl, carbonyl, aryl, or heteroalkyl groups.
 6. The compound of claim 3 wherein the subsituents of the aryl groups II or III are independently selected from the group consisting of 1-8 carbon atoms, halogen, cyano, amino, amido, sulfonyl, carbonyl, aryl, or heteroalkyl groups.
 7. A yellow fluorescent material comprising a compound according to claim 1 .
 8. A red fluorescent material comprising a compound according to claim 2 .
 9. A yellow fluorescent material comprising a compound according to claim 3 . 